Grants Funded

Abstract
There are over 1.7 million people within the United States currently suffering from some type of limb loss, and this number continues to grow by 185,000 each year. Typical upper extremity replacement limbs are passive prosthetic devices and provide little functional recovery beyond basic grasping. Newer prostheses that add additional control through using muscle activity of the patient's remaining muscle groups increase the utility of these replacement limbs. The current state of the art treatment allows subjects to have the greatest restoration of function through targeted reinnervation of muscle groups using nerve from the amputated limb. However, these devices have limited control options for prostheses with multiple degrees of freedom and are generally difficult to master. We have developed a regenerative peripheral nerve interface (RPNI) that creates a biologically robust and functional connection to the nerve in an amputated limb through the use of a graft of free muscle tissue. The graft is then sutured to the severed residual nerve, and electrodes are affixed allowing signals to be recorded from the nerve (epineural electrode), or the muscle (epimysial electrode). These electrophysiological signals are then used for control of a replacement robotic arm. We propose to quantify the effect of neuromuscular amplification in regenerative peripheral nerve interfaces. Using a rodent model developed within our research group, we will quantify the information content that can be recorded by using a neuromuscular "amplifier". Nerve signals will be sampled after they have been "amplified" by the muscle, thereby providing a higher signal-to-noise ratio without signal loss from electrode encapsulation and tissue trauma from direct epineural electrode placement. Further, the use of epimysial electrodes should increase the overall long-term stability of the interface, compared to current methods utilizing penetrating electrodes either in the nerve or muscle.

Biography
Nicholas Brandon Langhals, PhD serves as an Assistant Research Scientist in the Neuromuscular Lab within the Plastic Surgery Section of the Department of Surgery at the University of Michigan. Dr. Langhals received both his Master's of Science in Engineering as well as Doctorate of Philosophy (PhD) in biomedical engineering from the University of Michigan (Ann Arbor, MI). His Bachelor's of Science in Engineering was obtained in bioengineering from Arizona State University. Dr. Langhals has worked as a Senior Research Engineer within the Center for Neural Communication Technology, served as a consultant for Neuronexus Technologies (Ann Arbor, MI) and Biotectix (Ann Arbor, MI), and recently founded Rhythm Solutions, Inc. Dr. Langhals’ previous research efforts were focused on cortical brain-machine interfaces, cortical mapping, direct brain drug delivery, electrode development and characterization, as well as neural signal analysis. He is now applying those skills towards the development of electrode technology and signal processing techniques for neuroprosthetic, cardiac, and other electrophysiological interfaces. One of his two main efforts is focused around the development of regenerative peripheral nerve interfaces that have the potential to be used for control of replacement robotic appendages in amputees as well as for extracting control signals for wheelchairs or computer cursors. His secondary efforts are focused around the development of real-time processing strategies for mapping atrial fibrillation from intracardiac electrodes.